Denise,

You probably have a different species than the one I've been fighting, (Erigeron divergens, from the Tucson, AZ area). In the desert they would form small stands near intermittent streams, but in the garden, mine spread from seed like crazy. Just one plant left to go to seed can produce a 100 seedlings or more the next year.

If yours are native to your area and have their spread checked by other native plants and conditions you can probably leave them be. If they're introduced I think I'd pull them.

Mike

This is one of our few native annuals. In my garden it pops up in different places in different years but never gets aggressive. I happen to love it, so I leave it wherever it appears.

I love the white daisy fleabane. I've been trying to find a place where I can buy it. If it's a weed, I much prefer it to the weeds I've got.

I love it. I have several versions, pink, white, small, large blooms. In Michigan some forms are threatened. They aren't trouble in Michigan. They are easy to pull out by their long stalks, unlike dandlions. I am trying to increase these cuties. Just sweet flowers that keep on blooming.

i wish I could get a hundred offspring but they self limit on my property